A study reveals an unexpected effect of long-term Covid...that may explain the secret of brain fog

Listen to the article. The audio text is automated, generated by an automated system

A preliminary study published in the eBioMedicine journal, and whose details were reported on the Science Alert website, revealed changes in the brains of people with long-term Covid-19 disease, which may explain some of the most common and disabling symptoms of the condition, such as memory decline, slow movement, and loss of motivation.

The Canadian study relied on 24 people with long-term Covid, and compared their results with healthy people of the same age group. The results showed that patients who suffered from more severe symptoms recorded greater changes in the endings of nerve cells associated with dopamine, a neurotransmitter that plays a pivotal role in regulating motivation, learning, and feelings of reward.

Psychiatrist Jeffrey Mayer, from the Brain Health Imaging Center in Canada, said that the results provide strong evidence of the possibility of a loss or decline in the function of dopamine-secreting neurons in some people with long-term Covid.

Dopamine is one of the most important chemical transmitters in the brain, and is linked to what is known as the reward system, which is responsible for feelings of pleasure and motivation. Disruption of this system in various neurological diseases leads to symptoms that include loss of motivation, slow movement, and memory problems, which are symptoms that a number of long-term Covid patients complain of.

Previous studies related to the condition focused on brain inflammation and immune changes associated with the disease, but the new study is one of the first to directly investigate the possibility that dopamine-producing neurons may be affected.

Researchers believe that there is more than one possible mechanism for this effect. Some long-term Covid patients show signs of brain immune cell activity that can affect synapses and lead to their damage. Also, the SARS-CoV-2 virus may theoretically be able to directly affect dopamine-secreting neurons, since they contain receptors that may allow the virus to enter or bind to them.

The study indicated that targeting dopamine pathways may open the door to a new therapeutic approach for those infected with long-term Covid, in a shift from current therapeutic paths that do not focus on improving the function of these neurons.

The researchers relied on brain imaging techniques that measure proteins found in the endings of dopaminergic nerves, a method that does not directly reveal the number of nerve cells, but it allows studying their changes in living patients.

Final confirmation of the extent of the loss of dopaminergic neurons requires examination of brain tissue after death. A previous small autopsy study had found a decline in the numbers of these cells in those who died due to severe Covid-19, but its results were affected by other factors such as advanced age and the presence of early indicators of dementia or Parkinson’s disease in some participants.

The researchers believe that if the results are confirmed in larger studies, it may become possible to test medications currently used to treat Parkinson's, such as levodopa, to improve some symptoms of long-term Covid. However, scientists warn against rushing to use these medications due to their potential side effects, in addition to the fact that their benefits may be limited to specific categories of patients.

Researchers confirm that long-term Covid is not a uniform condition, as its symptoms vary greatly between patients, which means that a disturbance in the dopamine system may explain only a part of the cases, not all of them.